Re: [CentOS-virt] /var/lib/xenstored & Xen4CentOS
On 06/04/2015 08:32 AM, George Dunlap wrote:
> for i in {1..80} ; do xl create null.cfg name=\"t$i\"
> kernel=\"/boot/vmlinuz-3.18.12-11.el7.x86_64\" memory=\"40\"
> on_crash=\"preserve\" ; done
>
> And then used the shell snippet from the bug report to generate load:
>
> while true; do xl list &> /dev/null; usleep 5000;done
>
> With xenstored normally the CPU load was about 30%. Mounted under
> tmpfs, it was slightly smaller, around 20%, but swung around wildly.
> With oxenstored it was about 15%.
>
> This is with xfs as the filesystem.
>
> That doesn't seem big enough to warrant a lot of effort: if you can
> reproduce the 75% numbers from the bug report I'll pursue it further,
> otherwise I'll probably just leave it.
I'm actually more concerned about I/O wait than CPU usage. When shutting down
or starting a lot of guests the wait time could be significantly increased.
I only started to look into this because I was doing load testing and it was
taking much longer to shut everything down then it seemed like it should.
Running multiple versions of xl in parallel (especially xl destroy) can make
many, many backups of tdb such that there's hundreds of MB of backup copies.
--Sarah
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Re: [CentOS-virt] /var/lib/xenstored & Xen4CentOS
On Thu, Jun 4, 2015 at 11:57 AM, George Dunlap wrote:
> On Thu, Jun 4, 2015 at 6:03 AM, Sarah Newman wrote:
>> By default, /var/lib/xenstored is mounted tmpfs in centos 5 but this doesn't
>> appear to be true for Xen4CentOS. This can cause performance issues as
>> mentioned in https://bugzilla.redhat.com/show_bug.cgi?id=446089
>>
>> I'm not sure if this should be part of xencommons, but if not, adding a
>> tmpfs mount should probably be documented on the quick start wiki page.
>
> Sarah,
>
> Thanks for looking into this.
>
> Adding a tmpfs mount to xencommons, if using the C xenstored, might be
> a good idea -- I'll float that with upstream and see what they say.
>
> As an alternate, can you try using the ocaml-based oxenstored (which
> doesn't use the filesystem as its atomicity mechanism)?
>
> To use oxenstored:
> * Install the xen-ocaml package
> * Reboot dom0
> * Verify that oxenstored is running:
> # ps ax | grep xenstore
> 654 ?S 0:00 /usr/sbin/oxenstored --pid-file
> /var/run/xenstored.pid
>
> (On my to-do list is to get oxenstored into the core xen-runtime
> package, which would also resolve this situation, I believe.)
FWIW, I used the following shell snippet to create 80 VMs (which crash
immediately without an initrd but still take up space in xenstore):
for i in {1..80} ; do xl create null.cfg name=\"t$i\"
kernel=\"/boot/vmlinuz-3.18.12-11.el7.x86_64\" memory=\"40\"
on_crash=\"preserve\" ; done
And then used the shell snippet from the bug report to generate load:
while true; do xl list &> /dev/null; usleep 5000;done
With xenstored normally the CPU load was about 30%. Mounted under
tmpfs, it was slightly smaller, around 20%, but swung around wildly.
With oxenstored it was about 15%.
This is with xfs as the filesystem.
That doesn't seem big enough to warrant a lot of effort: if you can
reproduce the 75% numbers from the bug report I'll pursue it further,
otherwise I'll probably just leave it.
-George
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Re: [CentOS-virt] /var/lib/xenstored & Xen4CentOS
On Thu, Jun 4, 2015 at 6:03 AM, Sarah Newman wrote: > By default, /var/lib/xenstored is mounted tmpfs in centos 5 but this doesn't > appear to be true for Xen4CentOS. This can cause performance issues as > mentioned in https://bugzilla.redhat.com/show_bug.cgi?id=446089 > > I'm not sure if this should be part of xencommons, but if not, adding a tmpfs > mount should probably be documented on the quick start wiki page. Sarah, Thanks for looking into this. Adding a tmpfs mount to xencommons, if using the C xenstored, might be a good idea -- I'll float that with upstream and see what they say. As an alternate, can you try using the ocaml-based oxenstored (which doesn't use the filesystem as its atomicity mechanism)? To use oxenstored: * Install the xen-ocaml package * Reboot dom0 * Verify that oxenstored is running: # ps ax | grep xenstore 654 ?S 0:00 /usr/sbin/oxenstored --pid-file /var/run/xenstored.pid (On my to-do list is to get oxenstored into the core xen-runtime package, which would also resolve this situation, I believe.) Thanks, -George ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
[CentOS-virt] Kubernetes 0.18. in virt7-testing
Hi, kubernetes-0.18.0-0.2.git5520386.el7 is in virt7-testing repo [1]. Please test and feedback. [1] http://cbs.centos.org/repos/virt7-testing/x86_64/os/Packages/ -- Navid Shaikh IRC: nshaikh ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
